Heart pacemakers and other implantable medical devices include electronic components contained within an outer housing. The outer housing of the implantable medical device can be formed of an appropriate material to withstand implantation within a human body. Implantable electronics can be shielded from external sources of electromagnetic interference (EMI) using a filter.
Conventionally, a feed-through filter can be coupled to an implantable medical device such that feed wires of the device pass through the feed-through filter as close as practical to the to the input-output connector on the implanted device. For example, as illustrated in FIGS. 38 and 39, a conventional implantable system 10 can include a canister or ferrule 11 through which feed wires 12 pass in order to connect between external circuitry of an implanted device and internal circuitry of the implanted device. The canister 11 can include a bushing 13 to secure and protect the feed wires 12. Bonding material 14 can be used to secure the feed wires 12 in the canister 11.
A feed-though filter 15 can be disposed within the canister 11. Feed wires 12 completely pass through feed-through filter 15 to connect between the internal and external circuitry of the implanted device. The feed-through filter 15 can act as a capacitor such that the each of the feed wires 12 of the device is electrically connected to a respective set of electrode plates 16 and 17 within the feed-through filter by the electrically conductive via 18. Conductive plates 17 are interleaved between conductive plates 16 to produce the capacitance effect. However, such feed-through filters often require numerous intricate manufacturing steps and are susceptible to damage during manufacture and assembly prior to implantation.
Thus, a need exists for an improved electromagnetic interference filter for implantable medical devices. More particularly, it would be desirable to have a filter that can reduce manufacturing time, cost, and complexity while also improving installation reliability. While various implementations of electromagnetic interference filters for implantable medical devices have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.